Total knee arthroplasty (TKA) or total knee replacement is a common orthopedic procedure in which damaged or diseased articular cartilage and/or bone of the knee is replaced with a prosthesis. In a TKA, a surgeon generally selects one of several different categories of total knee prostheses for implantation depending on the needs of the patient. Prior to implantation of such prosthesis, a surgeon generally resects a portion of the patient's native tibia and femur so as to shape these bones to receive the particular prosthesis selected.
A hinged total knee prosthesis is one category of total knee prostheses. Hinge knee prostheses are typically the most constrained category of total knee prostheses as they most significantly limit the total range of motion of a patient's repaired knee. However, because of such constraint, hinge knee prostheses often provide the most stability and are, therefore, most useful to patients' who have severe joint instability caused by bone loss, ligament deficiencies, and the like. In this regard, hinge knee prostheses are often selected for patients undergoing a revision procedure in which a previously implanted prosthesis is replaced. This can be due to significant bone loss or ligament deficiencies at least partially caused by the previous prosthesis. In addition, hinge knee prostheses are also commonly selected for patients who have bone cancer, such as osteosarcoma, of the tibia and/or femur.
Performing a revision procedure to implant a hinge knee prosthesis can differ quite significantly from that of an oncology procedure to do the same. For example, in a revision procedure, a surgeon removes the previously implanted prosthesis exposing bone that had been shaped in a previous procedure. Although significant deformities can be present, the resected bone and bone deformities often do not extend beyond the metaphysis. So whatever bone stock remains is further shaped and bolstered to receive the hinge knee prosthesis.
In contrast, in an oncology procedure, a patient may have a cancerous tumor in the distal femur or proximal tibia. In order to remove such cancer, a significant portion of the patient's bone is removed along with the cancer. In this regard, resection may be performed along the bone's diaphysis thereby removing the entire proximal tibia or distal femur. In addition, the patient often has a healthy, pristine bone opposite that of the malignant bone. Thus, in order to perform the appropriate replacement, the resected malignant bone must be rebuilt and the pristine bone must be shaped to receive the appropriate components.
Despite the differences between revision and oncology TKA procedures there is some commonality between these procedures in that the tibia and femur are typically resected first, and then a hinge knee trial is assembled onto the resected bone to assess patellofemoral kinematics and joint capsule tightness. If adjustments need to be made, the trial is disassembled and further resections are performed, which may result in an iterative process of assembly, disassembly, and resection that tends to raise the joint line. In addition, the assembly and disassembly of the hinge trial, which often requires an axle to be inserted into a femoral component from a lateral or medial side thereof and through a bearing plate disposed between adjacent condylar portions of the femoral component, can be time consuming which can result in increased risk of infection and overall recovery time.
Numerous instruments, such as trials, cutting guides, and the like, have been made available to help perform hinge knee prosthesis implantation for both revision and oncology procedures. However, such instruments often differ significantly to account for the differences between the procedures. Thus, a manufacturer is often required to offer a large assortment of instrumentation that results in significant manufacturing costs.
In addition, such instruments are provided to an operating theater in sets. Such sets themselves are often comprised of numerous instruments. For example, a currently performed hinge knee procedure may require about 24 instrument cases and 28 instrument trays. These instruments may be stored, cleaned, packaged, and shipped by the manufacturer to the healthcare facility in which the procedure is to take place. In some instances, the instruments may be stored and sterilized at the healthcare facility itself. The demands of manufacturing, storing, maintaining, sterilizing, packaging, shipping and tracking such a diverse, complicated and large quantity of instruments can be expensive, particularly in a world that is increasingly demanding cheaper surgical procedures. For example, a set of instruments for performing a TKA procedure may cost about 40,000 USD to manufacture. These instruments may then be placed into circulation. While in circulation, these instruments must be stored, repaired, sterilized, packaged and shipped numerous times over contributing to the overall costs of the instruments. The more instruments provided in each set, the greater the life-cycle costs become, which may reflect back to the cost of the TKA procedure.
Therefore, further improved instruments and consolidation of instruments for use in hinge knee procedures is desired.